Airfoil bladed fans



March 2, 196s D. ARfEwnz 3,171,586

AIRFOIL BLADED FANS Filed Dec. 3l, 1963 by m1 CL PM dzdazey United States Patent O 3,171,586 Aml, BEADED FANS Daniel Ariewita, Framingham, Mass., assigner to Westinghouse Electric Corporation, Pittsburgh, ila., a corporation of Pennsylvania Filed Dec. 31, 1%3, Ser. No. 334,770 Qiairns. (El. 23h-134) This invention relates to centrifugal fans having rotors with airfoil blades bolted thereto, and has as an object to improve the bolting of such blades to such rotors.

It has been a practice to bolt airfoil-shaped blades of heavy duty, centrifugal fans to the side and back plates of the rotors of such fans with long bolts which extend through the side and back plates. This has not been entirely satisfactory since line reaming through a side plate, blade end plates and a back plate becomes inaccurate and results in a twisting of the assembly; an increase in blade width results in greatly increased bolt detiection, and intermediate bolt support requirements; the stress loading on the side and back plates produced by the bolts becomes significant as bolt size and length increase, and differential expansion between a bolt and a blade becornes signiicant at elevated temperatures, and becomes more troublesome as bolt length increases.

This invention overcomes the disadvantages of such a bolting method by welding hollow bosses spaced apart near the centerline of a blade, to the blade end plates; by shaping the cavities within the bosses as nut pockets; by placing nuts within the nut pockets, and by placing studs having threaded inner ends from the outer surfaces of the side and back plates through holes drilled in such plates, and threading the inner ends of the Studs in the nuts. Nuts threaded on the outer ends of the studs tighten the assemblies against the side and back plates. This results in hard joints, and the short studs are subjected to shear and tension with no bending.

This invention will now be described with reference to the annexed drawings, of which:

FIG. l is a fractional front view of a rotor of a fan embodying this invention, with a portion of the side plate and a portion of the adjacent end plate removed;

FIG. 2 is a partial sectional View along the lines 2-2 of FIG. 1;

FIG. 3 is a section along the lines 3 3 of FIG. 2, and

FIG. 4 is a view of a portion of the inner side of the fan blade, showing a slot therein, and a nut in the slot.

Rotor of a centrifugal fan, has a conventional side plate 11 and a conventional back plate 12. A hollow airfoil blade 13 has a nose 14 located near inlet opening 1S of the rotor, and has a tip 16 near the periphery of the rotor. The blade has in both ends, conventional end plates 17 shaped to conform to the interior of the blade, welded to the blade. The drawings show a blade end plate 1'/ in the side plate end of the blade only, but there would be another blade end plate at the back plate end of the blade, and the construction described in the following is present at the back plate end of the blade as well as at the side plate end of the blade.

Hollow bosses 18, 19 and 20 are spaced apart near the centerline of the blade, and are welded to the inner surface of the end plate 17. The cavities Within the bosses are shaped to have a small clearance around nuts 21, 22 and 23. The inner side of the blade has slots 24, 25 and 25 with rounded ends into which rounded ends of the nuts extend, the nuts being shaped conformal with the slots, and filling the slots, with the inner sides of the nuts being iiush with the inner side of the blade for reducing friction with the air passing the inner side of the blade. Since the nuts fill the slots, no foreign particles entrained in the air can enter the blade.

The side plate 11 is drilled to receive studs 26, 27 and 28 which have inner ends threaded into the nuts 21, 22 and 23 respectively. The studs have threaded outer ends extending beyond the outer surface of the side plate 11, on which are threaded nuts 30, 31 and 32. The nuts 21, 22 and 23 are drilled to receive lock pins 34, 35 and 36 respectively, which bind threads on the inner ends of the studs 2d, 27 and 2S respectively, for preventing the studs from turning within the nuts 21, 2.?. and 23 respectively, after they have been threaded sufficiently into the latter. The pins 3d, 35 and 3d are inserted Within the nuts 21, 22 and 23 respectively, through the slots 24, 25 and 26 respectively.

The nuts 3d, 31 and 32 when pulled up tightly against the outer surface of the side plate 11, pull the end plate 17 tightly against the side plate 11 for securing the fan blade thereto. The blade is secured to the back plate 12 by studs d0, 41 and 42 having nuts 43, dit and 45 respectively, on their outer ends, which studs correspond to the studs 26, 27 and 2S respectively, and which nuts correspond to the nuts 30, 31 and 32 respectively, the blade being secured to both side and back plates in the same manner.

What is claimed is:

1. A rotor for a centrifugal fan comprising aligned, spaced-apart, side and back plates, a hollow airfoilshaped blade extending between and in contact at its ends with the inner sides of said plates, an end plate in one of said blade ends and welded to said blade, said end plate having its outer side in contact with the inner side of one of said iirst mentioned plates, a plurality of hollow bosses within said blade and spaced apart along the length thereof, said bosses having outer sides in contact with the inner side of said end plate, a nut within the cavity of each of said bosses, and a plurality of studs extending through said one plate into respective ones of said cavities, said studs having inner ends threaded into respective ones of said nuts.

2. A rotor as claimed in claim l in which one side of said blade has slots into which adjacent sides of said nuts tit.

3. A rotor as claimed in claim 2 in which said nuts have pins extending from said adjacent sides of said nuts into said nuts in contact with threads on respective inner ends of said studs.

4. A rotor as claimed in claim 3 in which said studs have threaded outer ends extending outwardly of the outer side of said one plate, and have nuts threaded on said outer ends.

5. A rotor as claimed in claim 1 in which said studs have threaded outer ends extending outwardly of the outer side of said one plate, and have nuts threaded on said outer ends.

References Cited in the le of this patent UNITED STATES PATENTS 2,774,308 Uhander et al Dec. 1S, 1956 FOREIGN PATENTS 803,551 Germany Apr. S, 1951 720,956 Great Britain .Tune 21, i952 

1. A ROTOR FOR A CENTRIFUGAL FAN COMPRISING ALIGNED, SPACED-APART, SIDE AND BACK PLATES, A HOLLOW AIRFOILSHAPED BLADE EXTENDING BETWEEN AND IN CONTACT AT ITS ENDS WITH THE INNER SIDES OF SAID PLATES, AN END PLATE IN ONE OF SAID BLADE ENDS AND WELDED TO SAID BLADE, SAID END PLATE HAVING ITS OUTER SIDE IN CONTACT WITH THE INNER SIDE OF ONE OF SAID FIRST MENTIONED PLATES, A PLURALLITY OF HOLLOW BOSSES WITHIN SAID BLADE AND SPACED APART ALONG THE LENGTH THEREOF, SAID BOSSES HAVING OUTER SIDES IN CONTACT WITH THE INNER SIDE OF SAID END PLATE, A NUT WITHIN THE CAVITY OF EACH OF SAID BOSSES, AND A PLURALITY OF STUDS EXTENDING THROUGH SAID ONE PLATE INTO RESPECTIVE ONES OF SAID CAVITIES SAID STUDS HAVING INNER ENDS THREADED INTO RESPECTIVE ONES OF SAID NUTS. 